Campaigners want urgent action to address the problem and on Tuesday a petition will be submitted to Scotland's Environment Secretary Roseanna Cunningham calling for the introduction of a deposit return scheme for drinks containers in Scotland.

Tisha Brown, oceans campaigner at Greenpeace UK, said: "It cannot be right that our beaches, seas and the stunning wildlife they are home to should become the final dumping ground for throwaway plastic bottles and other plastic trash.

"With a truckload of plastic entering the ocean every minute, we need urgent action from governments and from major soft drinks companies which produce billions of single-use plastic bottles every year, like Coca-Cola, to stop the flow of plastic into the sea."

The petition handover coincides with the arrival of Greenpeace ship the Beluga II in Edinburgh to present the initial findings from its mission, carried out in May and June.

Researchers found plastic strewn on more than 30 beaches in remote areas, microplastics in the foraging grounds of basking sharks and seabirds, and animals entangled in rubbish.

Pollution was discovered in the nests and beaks of seabirds in internationally-significant colonies on the Bass Rock, Isle of May and the Shiant Isles.

The expedition conducted more than 40 scientific trawls in remote and biodiverse areas home to wildlife including seals, puffins and whales, with early analysis revealing plastic in multiple samples.

The samples will be sent to the Greenpeace research laboratories at Exeter University for full analysis with complete results to be published later this year.